Whenever i try and install Internet Explorer 7 it says the following...

"Setup could not verify the integrity of the files needed for the installation. Make sure the Cryptographic Service is running on your computer".

Can anyone help me and tell me what this error is about and what the cryptographic service is

plz and ty

I've never heard of Cryptographic Service before, but my guess is that it is a Windows Service. Services are programs, but run in a special way (which I'm not sure of).

You can change settings for services in the Services Management Console. To open it, you click Start > Run and then type services.msc in the box and click OK (I'm not sure of this because my computer isn't working properly so I can't test it).

In Services, in the right hand side pane, look for Cryptographic Service in the list (there will be heaps of services). You might have to scroll the list to find it. Click it, and then, in the left pane, observe the status of the service. If it's running, restart it, and if it isn't running, start it.

ahhh found it thanks
edit: Still didnt work though, oh well i got firefox neway

If this still keeps happening with the cryptographic service running, it is probably because your catalog database is corrupted.  This is a fairly common problem and Microsoft has published a knowledge base article on how to fix it. 

The problem can appear with various error messages, in many different situations, so don't be discouraged by the length of the KB article and just skip to the "Resolution" part.